Away from fires, deadly smoke risks are intensifying

It kills more people each year than car accidents, war or drugs. This invisible killer is air pollution from sources like cars and trucks or factory smokestacks.

But as wildfires intensify and become more frequent in a warming world, smoke from these fires is becoming a new and deadly source of pollution, health experts say. By some estimates, wildfire smoke, which contains a mix of dangerous air pollutants such as particulate matter, nitrogen dioxide, ozone and lead, already causes up to 675,000 premature deaths per year around the world, as well as a range of respiratory, heart and other diseases.

Research shows wildfire smoke starting to rise erode the world’s progress in cleaning pollution from exhaust pipes and chimneys, As climate change intensifies fires.

“It’s heartbreaking, it really is,” said Dr. Afif El-Hasan, a pediatrician specializing in asthma care at Kaiser Permanente in Southern California and board director of the American Lung Association. The wildfires “are endangering our homes, but also our health,” said Dr. El-Hasan, “and the situation is only going to get worse.”

Those health concerns came to the fore this week as wildfires ravaged the Los Angeles area. Residents They began to return to their neighborhoodsmany of them covered in smoldering ash and debris, to assess the damage. Air pollution levels remained high in many parts of the cityeven on the coast northwest of Los Angeles, where the air quality index rose to “hazardous” levels.

Los Angeles, in particular, has seen air pollution at levels that could be raising daily mortality by 5 to 15 percent, said Carlos F. Gold, an expert on the health effects of air pollution. University of California at San Diego.

That means current death counts, “although tragic, are probably greatly underestimated,” he said. People with underlying health conditions, as well as the elderly and children, are particularly vulnerable.

The rapid spread of this week’s fires to dense neighborhoods, where they burned homes, furniture, cars, electronics and materials like paint and plastic, made the smoke more dangerous, said Dr. Lisa Patel, a pediatrician in the Area. San Francisco Bay and the executive director of the Medical Society Consortium on Climate and Health.

A recent study found that even in homes that are saved from destruction, smoke and ash that drifts inside could stick to carpets, couches and drywall, creating health risks which can last for months. “We’re breathing in this toxic mixture of volatile organic compounds and polycyclic aromatic hydrocarbons and hexavalent chromium,” Dr. Patel said. “All this is harmful.”

Meanwhile, increasingly intense and frequent fires are altering experts’ understanding of the health effects of smoke. “Wildfire season is no longer a season,” said Colleen Reid, who researches the health effects of air pollution from wildfires at the University of Colorado Boulder. “We have fires throughout the year that repeatedly affect the same population.”

“The health impacts are not the same as if you were exposed once and then didn’t do it again for 10 years,” he said. “The effects of this is something we don’t really know yet.”

A 2022 United Nations report concluded that the risk of devastating wildfires around the world would increase in the coming decades. Warming and drying caused by climate change, along with development in places vulnerable to fire, were expected to intensify a “global forest fire crisis”the report said. Both the frequency and intensity of extreme wildfires have more than doubled in the last two decades. In the United States, the average area burned per year ha has increased since the 1990s.

Now, pollution from wildfires is reversing what had been a decades-long improvement in air quality brought about by cleaner cars and energy generation. Since at least 2016, in nearly three-quarters of continental U.S. states, smoke from wildfires has eroded about 25 percent of the progress in reducing concentrations of a type of particulate matter called PM 2.5. a nature study in 2023 found.

In California, the effect of wildfire smoke on air quality is counteracting advances in public health caused by a decrease in air pollution from cars and factories, state health officials have found. (By releasing carbon dioxide and other planet-warming gases into the atmosphere, wildfires are themselves a major contributor to climate change: Wildfires that devastated Canada’s boreal forests in 2023 produced more greenhouse gases than burning fossil fuels in all but three countries.)

“It’s not a pretty picture,” said Dr. Gold of UC San Diego, who participated in the Nature study. If emissions of planet-warming gases continue at current levels, “we have some work that suggests mortality from wildfire smoke in the United States could increase by 50 percent,” he said.

One silver lining is that the Santa Ana winds that so fiercely fueled the flames in recent days have been blowing some of the smoke toward the ocean. This contrasts with smoke from the 2023 Canadian wildfires. who went to New York and other American states hundreds of kilometers away, causing spikes in emergency room visits for asthma.

At one point that year, more than a third of Americans, from the East Coast to the Midwest, were under air quality alerts due to smoke from the Canadian wildfires. “We are seeing new and worsening threats in places that are not used to them,” said Dr. Patel, the pediatrician.

The new normal is causing changes in healthcare, Dr. Patel said. More health systems are sending air quality alerts to vulnerable patients. At the small community hospital where she works, “every child who comes in with wheezing or asthma, I talk to them about how air pollution is getting worse because of wildfires and climate change,” she said.

“I teach them how to check the air quality and tell them they should order an air purifier,” Dr. Patel added. It also warns that children should not be involved in cleaning up after a wildfire.

Scientists are still trying to understand the full range of wildfire smoke’s health effects. A big question is how much of what researchers know about vehicle exhaust and other forms of air pollution applies to wildfire smoke, said Mark R. Miller, a researcher at the University’s Center for Cardiovascular Sciences. of Edinburgh, who directed a recent global survey of climate change, air pollution and forest fires.

For example, exhaust particles “are so small that when we breathe them in, they go deep into our lungs and are actually small enough to pass from our lungs into our blood,” he said. “And once they’re in our blood, they can be transported through our body and start to build up.”

That means air pollution affects our entire body, he said. “It has effects on people who have diabetes, it has effects on the liver and kidneys, it has effects on the brain, on pregnancy,” he said. What is still unclear is whether pollution from wildfires has all of those same effects. “But it’s likely,” he said.

Experts offer a series of tips for people living in smoky areas. Please monitor air quality alerts and follow evacuation orders. Stay indoors as much as possible and use air purifiers. By venturing outside, wear N95 masks. Don’t do strenuous exercise in bad air. Keep children, the elderly and other vulnerable groups away from the worst smoke.

Ultimately, addressing climate change and reducing all types of air pollution is the way to reduce the overall health burden, said Dr. El-Hasan of the American Lung Association. “Can you imagine how much worse things would be if we hadn’t started cleaning up the emissions from our cars?” said. “I’m trying to think, glass half full, but it breaks my heart and worries me.”